Stock Seats and Cage/harnesses question

when i had the stock seats in my demon i did not have to have them bolted to the roll bar but i did have to have the shoulder straps go through the seat back. that required a slot 3 1/2" wide and 1/2" high in the plastic which was positioned just at the seam in the front so i could just cut the stitching and slip lthe belts through.